The present invention relates to the transfer of image data from one reconstruction agent to another. The invention finds particular application in conjunction with tomographic (CT) scanners and will be described with particular reference thereto. However, it is to be appreciated that the invention is also applicable to other types of diagnostic imaging, image reconstruction, image and data processing, and the like.
In the field of computerized tomographic scanners, the accurate and rapid reconstruction of images is of utmost importance. One of the major drawbacks in accurate image reconstruction has been the amount of time necessary to complete the image reconstructions for each scan of a multiscan procedure. The image from one scan is substantially completed before the next scan is initiated. The longer the time necessary to complete the image and initiate the next scan of the procedure, the more likely procedure degrading occurrences, such as patient movement, become.
Increasing the speed at which acquired data is reconstructed results in a corresponding increase in image quality. The speed at which an image is reconstructed is dependent upon the time necessary to pass data among the various reconstruction agents. The speed of this reconstruction is directly related to the accessibility of data required by an agent stored in a memory location.
At present, computer tomographic and nuclear magnetic resonance reconstruction systems employ a global memory architecture, as represented in U.S. Pat. No. 4,654,797 to Fujita, et al. In a global memory architecture, all data is located in a main memory. The various agents must gain access to the main memory to acquire data for the performance of its operations and to return the partially processed data. The moving of data into and out of the global memory by many agents causes congestion and limits processing speed. The various components that perform out of global memory operations, access the global memory by first specifying an address and then either reading or writing data to that specific address.
All communication between the various agents or components necessary in the reconstruction process is done through accessing of the main memory. Therefore, the speed at which the individual agents or components can function is bound to the speed of the main memory. Additionally, although some special actions in the reconstruction process can be performed concurrently there is a hierarchy or priority of performance of the agents `or the components` functions.
While the processing agents may be capable of processing independently, all memory access to acquire data must be outputted serially from the main memory. Thus, some agents must at times sit idle and wait for data while other agents are accessing memory.
The global memory architecture presently used in computed tomographic and nuclear magnetic resonance imaging creates a back-up or bottle-neck of agents or components wishing to access the main memory. Implementation of a hierarchial system for access to main memory among the various reconstruction agents implies a slow down in the ability of the various agents to acquire the necessary data to perform their required function.
In accordance with the present invention, an architecture which allows the various agents or components faster access to data is provided.